New research reveals how dragonfly wings obliterate bacteria without the help of antibiotics

Surfaces that obliterate bacteria have always been in demand. Last year, for instance, a group of Dutch scientists used a new type of plastic resin infused with quaternary ammonium salts to develop a 3D-printed tooth that is reportedly capable of killing up to 99-percent of oral bacteria. As part of a new study, researchers from Nigeria and Australia have created yet another bacteria-annihilating surface, featuring a “bed of nails” that literally rip these pesky microbes apart.

Bacteria-Killing Abilities Of Dragonfly Wings

Built using black silicon, this nano-textured surface (or NTS) contains a series of nanopillars of different heights. The inspiration for the breakthrough, according to the team, actually came from something quite unexpected, to some extent even ordinary: dragonfly wings. The insect’s wings possess a similar web of nanostructures that are in turn responsible for killing bacteria.

Up until now, it was believed that a ‘bed of nails’ nano-textured surface destroys microorganisms by perforating their cellular membrane. In the new research, however, the scientists have provided a different explanation for this unusual phenomenon. Aided with a variety of microscopy techniques, the team meticulously examined the structure of dragonfly wings, which led them to uncover a hitherto-unknown clue: the nanopillars on the wings’ surface are not of the same height.

Nanoscopic Pillars On The ‘Bed of Nails’ Surface

Extracellular Polymeric Substances (EPSs) that connect the bacterial membrane to the nanopillars

This piece of information is indeed extremely important, since synthetic ‘bed of nails’ surfaces almost always contain nanopillars of equal height, and are therefore not as effective in killing bacteria as the naturally-occurring counterpart. Unlike what was previously believed, the microbial membrane doesn’t come in direct contact with the nanoscopic pillars. During the analysis using E.coli, the scientists discovered that the bacteria get connected to the nanostructures via molecules of extracellular polymeric substance (EPS).

The surface’s adhesive forces causes the bacterial membrane to rupture and deflate

Once the microbes get implanted, they become a part of the surface itself. Any adhesive force can therefore contort the bacterial membrane. When they start moving, the resultant pull puts pressure on the EPSs and can at times rupture the cellular wall of the microorganisms. This in turn causes it to deflate, leading to its death.

Recently published in the ACS Applied Materials & Interfaces journal, the research is currently limited to only E.coli, which is a Gram-negative bacterium containing two membranes. In order to acquire credibility, the study will have to be wider in scope. The scientists will also have to check if the nanopillars’ efficiency in killing bacteria is affected by the amount of EPS present in the surface.